An automatic travel system enabling a vehicle to automatically travel has been developed as a new traffic system. For instance, in JP-A-H10-162285 discloses an automatic travel system. In this system, lane signal transmitters for each lane of an automatic travel road are disposed at given travel distance intervals in a freeway that is for exclusive automobile travel use and constructed as an automatic travel road. By contrast, two receivers that receive signals from the lane signal transmitters is provided in a lower right and lower left sides of a front bumper of the vehicle. The automatic travel system controls the steering, accelerator, and brakes of the vehicle for automatically traveling so that the respective lane signal transmitters on the freeway can be located at a center of the two receivers. Furthermore, a discrimination signal transmitter is disposed in each interchange of the freeway, while a car navigation system is mounted in the vehicle. Here, when a route to a destination is designated, the car navigation system determines whether it is an interchange at which the vehicle should exit from the freeway based on a signal from the discrimination signal transmitter. The car navigation system then notifies the driver of the determination.
In the above automatic travel road, the driver can be relieved of an operating load to a destination since the driver does not need to operate. However, the car navigation system that is disposed in the vehicle remains only a system that notifies the driver of whether it is an interchange where the driver should exit from the freeway.
Here, a car navigation system typically has a function of automatically searching for a route from the present position to a destination when the destination is set. In the above case where the vehicle capable of automatically traveling on the automatic travel road has a car navigation system, the car navigation system could preferentially select the automatic travel road as at least part of a route to the destination. This results in relieving the driver of an operating load or enhancing safe driving.